using System;

namespace Org.BouncyCastle.Asn1.X509
{
	/**
	 * Policy qualifiers, used in the X509V3 CertificatePolicies
	 * extension.
	 *
	 * <pre>
	 *   PolicyQualifierInfo ::= Sequence {
	 *       policyQualifierId  PolicyQualifierId,
	 *       qualifier          ANY DEFINED BY policyQualifierId }
	 * </pre>
	 */
	public class PolicyQualifierInfo
		: Asn1Encodable
	{
		internal readonly DerObjectIdentifier	policyQualifierId;
		internal readonly Asn1Encodable			qualifier;

		/**
		 * Creates a new <code>PolicyQualifierInfo</code> instance.
		 *
		 * @param policyQualifierId a <code>PolicyQualifierId</code> value
		 * @param qualifier the qualifier, defined by the above field.
		 */
		public PolicyQualifierInfo(
			DerObjectIdentifier	policyQualifierId,
			Asn1Encodable		qualifier)
		{
			this.policyQualifierId = policyQualifierId;
			this.qualifier = qualifier;
		}

		/**
		 * Creates a new <code>PolicyQualifierInfo</code> containing a
		 * cPSuri qualifier.
		 *
		 * @param cps the CPS (certification practice statement) uri as a
		 * <code>string</code>.
		 */
		public PolicyQualifierInfo(
			string cps)
		{
			policyQualifierId = PolicyQualifierID.IdQtCps;
			qualifier = new DerIA5String(cps);
		}

		/**
		 * Creates a new <code>PolicyQualifierInfo</code> instance.
		 *
		 * @param as <code>PolicyQualifierInfo</code> X509 structure
		 * encoded as an Asn1Sequence.
		 */
		private PolicyQualifierInfo(
			Asn1Sequence seq)
		{
			if (seq.Count != 2)
				throw new ArgumentException("Bad sequence size: " + seq.Count, "seq");

			policyQualifierId = DerObjectIdentifier.GetInstance(seq[0]);
			qualifier = seq[1];
		}

		public static PolicyQualifierInfo GetInstance(
			object obj)
		{
			if (obj is PolicyQualifierInfo)
			{
				return (PolicyQualifierInfo) obj;
			}

			if (obj is Asn1Sequence)
			{
				return new PolicyQualifierInfo((Asn1Sequence) obj);
			}

			throw new ArgumentException("unknown object in GetInstance: " + obj.GetType().FullName, "obj");
		}

		/**
		 * Returns a Der-encodable representation of this instance.
		 *
		 * @return a <code>Asn1Object</code> value
		 */
		public override Asn1Object ToAsn1Object()
		{
			return new DerSequence(policyQualifierId, qualifier);
		}
	}
}
